Systems, methods and/or devices are used to reduce anomalous charging current by selectively shunting biasing current away from a control terminal of a controlled device that conducts the charging current during a charging mode. In some embodiments, a power-control circuit includes: (1) a controlled device with a first terminal coupled to a power-supply node, a second terminal to provide a first output voltage, and a control terminal; (2) a current source to provide a biasing current to the control terminal of the controlled device during a charging mode; and (3) a selective current shunt to shunt a portion of the biasing current away from the control terminal of the controlled device in response to a determination that a charging current through the first and second terminals of the controlled device satisfies a threshold during the charging mode.
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1. A power-control circuit, comprising: a controlled device comprising a first terminal coupled to a power-supply node, a second terminal to provide a first output voltage, and a control terminal; a current source, distinct from the controlled device, to provide a biasing current to the control terminal of the controlled device during a charging mode, the biasing current to bias a charging current between the first and second terminals of the controlled device; a control circuit configured to determine whether the charging current between the first and second terminals of the controlled device satisfies a first threshold; and a selective current shunt configured to shunt a portion of the biasing current away from the control terminal of the controlled device in response to the determination that the charging current through the first and second terminals of the controlled device satisfies the first threshold during the charging mode.
A power-control circuit reduces anomalous charging current by selectively shunting current away from a transistor (the "controlled device") during charging. The circuit includes: a controlled device (transistor) connected to a power supply, outputting a voltage, and having a control terminal; a separate current source to provide current to the controlled device's control terminal, thus enabling charging; a circuit that checks if the charging current exceeds a threshold; and a current shunt that, when the threshold is exceeded, diverts some of the current away from the control terminal, slowing down the charging current.
2. The power-control circuit of claim 1 , wherein: the control circuit is configured to assert a control signal in response to the determination that the charging current satisfies the first threshold; the selective current shunt is configured to shunt a portion of the biasing current away from the control terminal of the controlled device in response to assertion of the control signal; and shunting a portion of the biasing current away from the control terminal reduces the charging current.
The power-control circuit described previously improves control using a signal. When the charging current exceeds the threshold, the control circuit sends a signal to the current shunt. The shunt then diverts current from the controlled device's control terminal *only* when it receives this signal. This diversion reduces the charging current. Essentially, the shunt only acts when explicitly told to by the control circuit, ensuring targeted control of the charging current.
3. The power-control circuit of claim 2 , wherein the selective current shunt comprises: one or more resistors; and a transistor situated in series with the one or more resistors between the control terminal of the controlled device and ground, the transistor comprising a control terminal to receive the control signal; wherein the transistor is configured to couple the control terminal of the controlled device to ground through the one or more resistors in response to assertion of the control signal.
The selective current shunt from the previous power-control circuit is implemented with a simple electronic switch: one or more resistors in series with a transistor are placed between the controlled device's control terminal and ground. When the control signal from the control circuit (see Claim 2) is received by the transistor, the transistor turns on, connecting the controlled device's control terminal to ground through the resistors, thus shunting current.
4. The power-control circuit of claim 2 , wherein the control circuit is to de-assert the asserted control signal in response to a determination during the charging mode that the charging current does not satisfy the first threshold.
The power-control circuit from Claim 2 includes the capability to disable the current shunt. If the charging current falls *below* the threshold while the control signal is active (shunt is diverting current), the control circuit deactivates the control signal. This tells the current shunt to stop diverting current, allowing the charging current to resume its normal rate.
5. The power-control circuit of claim 4 , wherein: the control circuit comprises a microcontroller; and the first threshold is programmable.
The power-control circuit from Claim 4 employs a microcontroller in the control circuit to offer flexibility. The threshold at which the control circuit starts and stops shunting current is programmable via the microcontroller. This allows the power-control circuit to be tuned for different charging characteristics and load requirements.
6. The power-control circuit of claim 2 , wherein the control circuit is to de-assert the asserted control signal in response to a determination during the charging mode that the charging current does not satisfy a second threshold that is lower than the first threshold.
The power-control circuit from Claim 2 uses *two* thresholds for more precise control. The control circuit activates the current shunt when the charging current exceeds a *higher* threshold (first threshold). It then deactivates the shunt when the charging current falls below a *lower* threshold (second threshold). This hysteresis prevents rapid on/off switching of the shunt.
7. The power-control circuit of claim 6 , wherein: the control circuit comprises a microcontroller; and the first and second thresholds are programmable.
The power-control circuit from Claim 6, which uses two thresholds, makes both of them programmable using a microcontroller. This provides even greater flexibility to adapt to a wider range of charging scenarios. Both the high and low thresholds can be adjusted via software.
8. The power-control circuit of claim 2 , further comprising current-sensing circuitry configured to monitor the charging current and provide a current-monitoring signal that indicates a value of the charging current to the control circuit.
The power-control circuit from Claim 2 adds current-sensing circuitry to accurately monitor the charging current. This circuitry provides a signal to the control circuit indicating the exact value of the charging current. The control circuit uses this information to determine whether to activate or deactivate the current shunt.
9. The power-control circuit of claim 1 , further comprising a diode, the diode comprising: an input coupled to the second terminal of the controlled device; and an output to provide a second output voltage to an energy-storage device.
The power-control circuit from Claim 1 further includes a diode connected to the controlled device's output. The diode's input receives the voltage from the controlled device, and its output provides a voltage to an energy-storage device, protecting the energy-storage device from reverse current flow.
10. The power-control circuit of claim 9 , wherein the energy-storage device comprises a capacitor bank.
The energy-storage device in the power-control circuit of Claim 9 is specifically a capacitor bank. The circuit uses the diode to provide a voltage to this capacitor bank.
11. The power-control circuit of claim 10 , wherein the capacitor bank is a capacitor bank of a solid-state drive.
The capacitor bank of the power-control circuit described in Claim 10 is used within a solid-state drive (SSD). The circuit provides power to the SSD's capacitor bank via the controlled device and diode.
12. The power-control circuit of claim 1 , wherein: the current source comprises a constant-current source; and the biasing current is a substantially constant current.
In the power-control circuit from Claim 1, the current source that biases the controlled device is a constant-current source. This means that it provides a stable, unchanging current to the control terminal, resulting in a more predictable charging current.
13. The power-control circuit of claim 12 , wherein the constant-current source comprises: a driver, coupled to the control terminal of the controlled device, to provide a bias voltage; a capacitor coupled to the control terminal of the controlled device; and a transistor, coupled between the capacitor and ground, to selectively couple the capacitor to ground in accordance with a voltage-ramp signal.
The constant-current source from the power-control circuit in Claim 12 consists of a driver that provides a bias voltage to the control terminal, a capacitor connected to the control terminal, and a transistor connected between the capacitor and ground. The transistor selectively connects the capacitor to ground based on a voltage ramp signal, thus providing a constant current.
14. A method of mitigating anomalous charging current, comprising: coupling a first terminal of a controlled device to a power supply, the controlled device comprising the first terminal, a second terminal, and a control terminal; biasing a charging current between the first and second terminals of the controlled device by providing a biasing current to the control terminal of the controlled device during a charging mode; determining whether a charging current flowing through the first and second terminals of the controlled device during the charging mode satisfies a first threshold; and shunting a portion of the biasing current away from the control terminal of the controlled device in response to a determination that the charging current satisfies the first threshold.
A method for reducing anomalous charging current involves connecting a transistor ("controlled device") to a power supply. During charging, a current source biases the transistor's control terminal to enable current flow. The method determines if the charging current exceeds a threshold. If it does, a portion of the biasing current is shunted away from the control terminal, reducing the charging current and preventing anomalies.
15. The method of claim 14 , wherein shunting a portion of the biasing current away from the control terminal of the controlled device reduces the charging current, and the shunting comprises: asserting a control signal in response to the determination that the charging current satisfies the first threshold; and providing the asserted control signal to a selective current shunt that couples the control terminal of the controlled device to ground when the control signal is asserted.
In the method of Claim 14, shunting the biasing current reduces the charging current. The shunting process involves: asserting (activating) a control signal when the charging current exceeds the threshold; and sending this control signal to a shunt circuit that connects the controlled device's control terminal to ground, thereby diverting current.
16. The method of claim 15 , further comprising: periodically making determinations as to whether the charging current satisfies a threshold; in response to a respective determination that the charging current satisfies a threshold, asserting the control signal for a duration corresponding to a time period between successive determinations; and in response to a respective determination that the charging current does not satisfy a threshold, de-asserting the control signal for the duration corresponding to the time period between successive determinations.
The method from Claim 15 continuously monitors the charging current. It periodically checks if the charging current exceeds the threshold. If it does, the control signal is activated for a set period (the time between checks). If the charging current is below the threshold, the control signal is deactivated for the same period. This ensures ongoing monitoring and adjustment.
17. The method of claim 15 , further comprising: determining that the charging current does not satisfy the first threshold; de-asserting the control signal in response to determining that the charging current does not satisfy the first threshold; and providing the de-asserted control signal to the selective current shunt; wherein the selective current shunt decouples the control terminal of the controlled device from ground when the control signal is de-asserted.
Expanding on the method in Claim 15, if the charging current falls *below* the threshold, the control signal is deactivated. This deactivation signal is sent to the current shunt, which then *disconnects* the controlled device's control terminal from ground, stopping the current diversion.
18. The method of claim 15 , further comprising: with the control signal asserted, determining that the charging current does not satisfy a second threshold that is lower than the first threshold de-asserting the control signal in response to determining that the charging current does not satisfy the second threshold; and providing the de-asserted control signal to the selective current shunt; wherein the selective current shunt decouples the control terminal of the controlled device from ground when the control signal is de-asserted.
In the method from Claim 15, once the control signal is active, if the charging current falls below a *second, lower* threshold, the control signal is deactivated. The deactivation signal is sent to the current shunt, which then disconnects the controlled device's control terminal from ground, stopping the current diversion. This adds hysteresis.
19. The method of claim 15 , further comprising: monitoring the charging current; based on the monitoring, generating a current-monitoring signal that indicates a value of the charging current; and providing the current-monitoring signal to a control circuit that asserts the control signal in response to the determination that the charging current satisfies the first threshold.
The method of Claim 15 includes monitoring the charging current to create a current-monitoring signal that represents its value. This signal is then sent to a control circuit, which uses the information to activate the control signal if the charging current exceeds the first threshold.
20. The method of claim 19 , further comprising setting a magnitude of the asserted control signal in accordance with a difference between the value of the charging current and the first threshold, wherein the magnitude of the asserted control signal is proportional to the difference between the value of the charging current and the first threshold.
In the method of Claim 19, the *strength* of the control signal is adjusted based on the difference between the actual charging current and the first threshold. A larger difference results in a stronger control signal, implying greater current shunting. The asserted control signal's magnitude is proportional to this difference.
21. The method of claim 14 , further comprising: coupling the second terminal of the controlled device to an input of a diode; and providing a voltage from an output of the diode to a capacitor bank.
The method of Claim 14 includes connecting the controlled device's output to a diode. The diode's output then provides a voltage to a capacitor bank, protecting the capacitor bank from reverse current.
22. A non-transitory computer-readable storage medium storing one or more programs configured for execution by a processor in a power-control circuit, the one or more programs comprising: instructions to provide a voltage-ramp signal to a current source to configure the current source to provide a biasing current to a control terminal of a controlled device during a charging mode, the biasing current to bias a charging current between first and second terminals of the controlled device; instructions to determine whether the charging current flowing through the controlled device during the charging mode satisfies a first threshold; and instructions to assert a control signal provided to a selective current shunt in response to a determination that the charging current satisfies the first threshold, wherein the selective current shunt shunts a portion of the biasing current away from the control terminal of the controlled device when the control signal is asserted.
A computer-readable medium contains instructions for a power-control circuit to mitigate anomalous charging current. The instructions tell the circuit to: generate a voltage-ramp signal to control a current source, which then provides a biasing current to a controlled device (transistor) during charging; determine if the charging current exceeds a threshold; and, if the threshold is exceeded, activate a control signal that commands a current shunt to divert current away from the controlled device.
23. The computer-readable storage medium of claim 22 , wherein the one or more programs further comprise instructions to de-assert the control signal in response to a determination that the charging current does not satisfy the first threshold, wherein the selective current shunt ceases to shunt the portion of the biasing current away from the control terminal of the controlled device when the control signal is de-asserted.
The computer-readable medium from Claim 22 *also* contains instructions to deactivate the control signal if the charging current falls below the threshold. This deactivation instructs the current shunt to *stop* diverting current away from the controlled device's control terminal.
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February 24, 2015
December 19, 2017
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